1. Field of the Invention
The present invention relates to a power driven screwdriver, and more particularly to a clutch mechanism for such a screwdriver which will transmit rotation from a drive motor to a spindle with a driver bit.
2. Description of the Prior Art
Such power driven screwdrivers may include a drive motor, a main gear rotated by the drive motor, an axially movable spindle having a driver bit secured thereto, and clutch means adapted to transmit and disconnect the rotation from the drive motor to the spindle. Basically, the clutch means includes a claw clutch mechanism which is composed of a fixed clutch member formed on the main gear and a movable clutch member mounted on the spindle and adapted to engage the fixed clutch member. Thus, axial movement of the spindle causes the movable clutch member to move into and out of driving engagement with the fixed clutch member. Such screwdrivers are disclosed, for example, in U.S. Pat. Nos. 2,940,488, 3,527,273 and 3,712,352.
In such screwdrivers using a simple claw clutch mechanism, however, the rotation of the spindle is restrained at the completion of a screw driving operation, thereby causing the clutch mechanism to temporarily repeat its engaging and disengaging operation. This will generate clanging sounds, giving unpleasant feeling to the operator, and cause early wear of the clutch mechanism.